The present invention relates to the field of providing power to a portable electronic device for operation and/or recharging of the device""s batteries. More specifically, the present invention relates to a method and apparatus for using a Universal Serial Bus xe2x80x9cUSBxe2x80x9d in a computer to power and/or recharge batteries in a portable electronic device.
Electronic devices typically require a power source for proper operation. Some devices obtain their power from a power cord coupled to a conventional power supply (such as a power receptaclexe2x80x94for example, 110 VAC). Devices having an input voltage requirement less than the supply voltage may also have a step down transformer or voltage reducing circuit. For example, a transformer or other voltage conversion or regulator circuitry may be used to reduce a supply voltage of 110 VAC, supplied by a power receptacle on a wall, to the required input voltage of the device. For devices requiring DC voltage, an AC/DC converter may also coupled between the step down transformer and the device.
Many electronic devices are also portable. While some portable electronic devices derive their power from batteries all the time, others derive their power from batteries while the device is in a portable mode and from a power cord coupled to a conventional power supply, as described above, when the device is near a permanent power supply. In either situation, the batteries will eventually run down if the device is operated when there is no power available from an outside source. When depleted, batteries of the rechargeable type can be recharged while non-rechargeable batteries must be replaced.
Portable electronic devices having rechargeable batteries may have their batteries recharged in one of three methods. First, batteries 10 within a portable electronic device may be physically removed from the device and placed in a battery recharge mechanism 12 until recharged, as illustrated in FIG. 1. The batteries are replaced in the device after being recharged. Second, batteries 10 may be recharged within a portable electronic 14 device (in this case a cellular telephone) via a power cord 16 (typically having a transformer 18 at one end of the power cordxe2x80x94typically the portion that plugs into the power source) coupling the portable electronic device to a conventional power supply 20, as discussed above and illustrated in FIG. 2. Third, batteries (not shown) within a portable electronic device 14 may also be recharged within device 14 while the device is placed within a charging receptacle 22 that is coupled, via a power cord 16, to a conventional power supply 20, as illustrated in FIG. 3.
The first method (shown in FIG. 1) is awkward and burdensome. The electronic device using the batteries is typically unusablexe2x80x94if of the battery only typexe2x80x94while its batteries are removed. There is also the potential problem of losing or damaging the batteries and/or the device itself through mishandling of the device or batteries and wear resulting from the continual process of removing and replacing batteries. If the device is of the type allowing operation from a power cord only, the mobility of the device is limited to the length of the power cord. The second method (shown in FIG. 2) is more convenient than the first method in that the batteries are not removed from the device while recharging, which facilitates immediate operation of the device, even if the batteries are not fully charged. There remains, however, the problem of having a recharge cord available when you need it. This is particularly so with small portable devices, such as cellular telephones, pagers, PDAs, etc., since the recharge cord itself may take up more storage space than the device itself. The third method (shown in FIG. 3) is the most convenient since the device can be simply placed in the charging cradle, recharging the batteries, while the device awaits reuse. One disadvantage of the charging cradles of the prior art is that they require a power cable coupling the charging cradle to a dedicated power source, such as a 110 VAC wall outlet or 12 VDC outlet (such as an automotive cigarette lighter power supply). Such recharging techniques are useless in situations where there are no, or insufficient, discrete power sources available to plug in the power cord of the charging cable.
The invention disclosed herein comprises a method and apparatus for using a universal serial bus xe2x80x9cUSBxe2x80x9d in a computer as a power source for a portable electronic device. In one embodiment of the invention, a computer having an external USB connector is coupled to the external power input connector on a portable electronic device, such as a cellular telephone. The computer is coupled to the cellular telephone via a cable having one end connected to a first connector and another end connected to a second connector, the first connector being connected to the USB connector on said computer, and the second connector being connected to external power input connector on said portable electronic device. The cable includes electronic circuitry for converting the voltage level supplied by the USB to a voltage level usable by the portable electronic device.
In one embodiment of the invention, the electronic circuitry is in the first connector. In another embodiment of the invention, the electronic circuitry is in the second connector. In still another embodiment of the invention, the circuitry is placed in the cable somewhere between the first and second connectors. In still yet another embodiment of the invention, a method and apparatus for using a universal serial bus in a computer as a power source and data port for a portable electronic device. The cable includes electronic circuitry for converting the voltage level supplied by the USB to a voltage level usable by the portable electronic device and for providing a data port between the computer and the portable electronic device. As with previously discussed embodiments of the invention, in one embodiment, the electronic circuitry is in the first connector. In another embodiment of the invention, the electronic circuitry is in the second connector. In still another embodiment of the invention, the circuitry is placed in the cable somewhere between the first and second connectors. Advantages of the invention include: elimination of the need for a separate power cable when the computer and the portable electronic device are used togetherxe2x80x94saving both cost of acquiring the additional power cable and travel space; a reduction from two dedicated power sources (one for computer and one for the portable electronic device) to one (for the computer only); and a convenient way to supply power to the portable electronic device from the computer""s batteries when no external power source is available for either device.